Double-action metal-drawing press



w. ERNST 2,146,535

ALI-DRAWING PRESS Feb. 7, 1939.

DOUBLE-ACTION MET Filed July 22, 1935 INVENTOR W44 TB EFNST iff w-f 6WPatented Febi 7 -1939 PLATE NT o neE 'nousm-sc'non mupnnawme muss WalterErnst, Mount Gilead, Ohio, assignor, by en Press meme ts, to TheHydraulic (ioi'pol-ation, 1110., Wilmington, DeL, a corporatlonofDelaApplication July 22,1935, sci-m so. 32,480

This invention relates to hydraulic pressesand circuits for actuatingthem, and in particular. to metal-drawing presses adapted to formarticles of various shapes from metal blanks while these 5 blanks areclamped in position by devices associated with the press.

One object of this invention is to provide a hydraulic double-actingpress having a pressing plunger and a clamping plunger, arranged to moveindependently of one another in one direction but interconnected inanother direction, the two plungers being arranged to be operated insequence.

Another object isto provide a hydraulic double-actingpress having apressing plunger and a clamping plunger, wherein the clamping plunger.is operated'initially and directly from-. a pump, through a shiitablevalve, the'flowof the pump being then redirected by the shifting 0 ofthis valve to thevmain or pressing plunger, which thereupon continuesits stroke and completes the pressing or drawing of the article from theblank. This is in contrast to themanner previously adopted of operating"the clamping 5 plunge'rs indirectly and simultaneously by fluiddisplaced from beneath the main pressing plunger, the excess above' apredetermined pressure being, discharged through a relief valve, withconsequent heating and loss of power because the use of the fluidbeneath the main piston to build up pressure on the blank holderrequired force which must be deducted fromthe available, pressing force.v

Another object is to provide a press of the type described above,wherein the pull-back side of the pressing plunger is given a smallerarea than the top area of the clamping plunger so that a rapid pull-backor retraction of the plunger is obtained, means being provided todischarge the excess of oil arising from the unequal arms in" volved. i

Another object is to provide a press of typedescribed, wherein anactuation of the press is entirely automatic, without need foradjustments upon, the part of the operator other than the reversal ofthe pump after the drawing operation has been completed. u a 4 Anotherobject is to provide a hydraulic circuit including a press having apressing plunger and a clamping plunger, the circuit having a pump andvalve system arranged to discharge the flow oi the pump first againstthe clamping plunger until a predetermined clamping pressure is reached,after which the discharge, of the pump is shifted' and applied to themain plunger, whereupon the pressing or drawing operation is completed.v

Another object is to provide such a press, j

wherein the valve for shifting the discharge of .the pump from theclamping plunger to the pressing plunger is operated by the pressurefluid directed thereto from a separate hydraulic device,

the latter being supplied with pressure fluid either from the main pumpor from anauxiliary source of pressure fluid. I

In the drawing: v I Figure 1 shows a preferred embodiment of the pressand circuit of my invention, this drawing being a front elevation,somewhat diagrammatic.

Figure 2' shows the additional apparatus in a modification of thecircuitshown in Figure 1, illustrating the use of an auxiliary pump forsupplying the fluid utilizedby the fluid control valve in actuating thefluid distributing valve.

Referring to the drawing in detail, the hydraulic press shown asembodyingmy invention, consists of a base I, which is connected by thetie rods ,2 to a top member 3, these being secured upon the tie rods 2by nuts 4,.threaded upon the threaded portions 5 thereof. Mounted uponthe base I is adie I, having a recess or forming portion I, ofthe ,shapenecessary for producing the particular article which it is desired tomake. The forming portion 1 is provided with a port 8 communicating witha pipe 9, the latter being arranged to provide compressed air forelecting the flnished article after the drawing operations have takenplace. The metal blank III is shown in position upon the die ,8 beforeany of the operations have taken place.

Mounted upon the top member 3 of 'the press is. a main drawing cylinderII and a pairv of clamping cylinders ii. The mouth of the main drawingcylinder ii is closed by a gland I3, ar-

partly" in section and ranged to compress a packing It, whereas themouths of the clamping cylinders II are provided with similar glands l4,arranged to compress packings I. These packings prevent the escape offluid from the clamping cylinders and drawing cylinder.

. Arranged to reciprocate in the main cylinder.

ii is the main piston rod il, havinga piston head l8, the piston rod I'I passing through the aperture in the gland i3 and packing Ill. To thelower end of the piston rod I1 is attached a; platen I! having a diemember .20 secured thereto. The ,die member 20 corresponds inconfiguration to the formingportion 1 of the die member C, but is ofopposite shape so that the clamping pistons 2| passing through theapertures in the glands I4 and packings I 8, and secured to a tie member22, which serves to interconnect their lower ends. Secured to the tiemember 22 is a clamping member 23,'as by the bolts 24. Beneath theclamping member 23 is arranged a blank holder 25, the latter restingupon the metal blank W from which the article is formed. An aperture 28in the blank holder 25 permits the passage of the die member-28therethrough.

The main piston head i8 is of the double-acting type, having a workingface 21 and a pull-back face 28, the latter being of annular shape andconstituting the space beneath the piston head I8 and surrounding thepiston rod i 1. Similarly,

the clamping pistons 2| are provided with working faces 29, In myinvention, by the arrangement subsequently to be described, the annularpull-back area 28 may be made substantially smaller than the combinedareas of the working Previously,

, it has been considered necessary to make the annular area 28 equal tothe combined areas of the working faces of the clamping pistons 2|, plusan additional area suflicient to sustain the weight of the moving partsso as to raise them against gravity. This construction, however, causeda slow action of the parts, whereas in my present construction thecomparatively small annular area of the pull-back portion 28 in itsreciprocation has a correspondingly smaller piston displacement volume.enables a very rapid withdrawal or pull-back of the main platen, becausea given quantity ofpressure fluid will retract the main piston fartherthan the clamping piston in the same period of time. The main platen isand the tie member 22.move downwardly in an independent manner, althoughsubstantially simultaneously. On the upward or retraction stroke,however, the main platen engages the tie member in the shoulderedportions 38, raising the tie member and with it the clamping pistons 2|.

Mounted on top of the main pressing cylinder H and clamping cylinders I2is the surgetank 3|, within which are surge valves 32 providingintercommunication between the surge tank and the tops of the cylindersII and I2. These surge valves 32 are of the type disclosed in my priorpatent, No. 1,892,568, issued December 27, 1932,

and the details thereof form no part of the present invention. Thesesurge valves 32 are arranged to permit fluid to be drawninto the top'portions of" the cylinders H and I2 during the downward stroke of theplungers l8 and 2| when the latter descend by gravity, thereby providinga prefllling of these cylinders and enabling a more. rapidsdescent ofthe plungersthan isenthe surge valves 32 along the lines 33. The lines83 are connected to thepipe 34, which in turn, is connected at itsleft-hand end through a T-coupling to the pressure release valve 35. Thelatter is connected by pipes 38 and 31 to the lay-pass This condition,therefore,

valve 38. A choke valve 38 serves to restrict the flow of fluid throughthe pipe 31 from the pressure release valve 35, whereas a similar chokevalve 48 on the pipe 4| discharges fluid directly into the surge tank 3|from the pressure release valve 35. The details of the pressure releasevalve 35, the by-pass valve 38, and their adjacent valves and pipes,form no part of the present invention, but a full disclosure thereof isfound in my prior patent, No. 1,956,758, issued May 1, 1934. The purposeof these valves is to assist in the releasing of the fluid pressure inthe main cylinder. prior to the opening of the surge valve on the returnstroke of the press, and also to by-pass the return of the pumpdischarge to the surge tank 3| through the by-pas's valve 38 durin therelease of the pressure fluid through the re-- lease valve 35.

The pipe 42 leads from the main cylinder II to the pressure releasevalve 35, and serves to convey the pressure fluid from the former.through the latter, into the surge tank 3|. This apparatus increases therapidity of "performance of the press upon its returnstroke.

The pipe ,34 at-its left-hand end leads into a T-coupling to which isconnected the check valve 44. The latter opens in a direction towithdrawn fluid from the surge tank 3| into the pipe 34. The right-handend of the pipe 34 is connected to the T-connection 43, from which runsthe pipe 45 to the port connection 48 of the pump 41. Continuing onwardfrom the port connection 48 is the pipe 48, leading to the check valve48, and thence through the line 58 to the port 5| in the main pressingcylinder below the plunger l8 thereof. The check valve 48 opens in adirection away from the pump "and toward the main pressing cylinderArranged to form a bridge connection around the check valve 49 are thelines 52 and 53, leading The relief valve 54 is provided with aplunger55, arranged to close the port 58 and respectively toward andaway from the relief valve 54.

urged in that direction by the coil spring 51, the

tension of which is changed by moving the screw plug 58. Thus fluidcoming into the port- 58, along the lines 58 and 53 can, if ofsufllcient pressure, overcomethe resistance of the coil spring 51, forceback the valve plunger 55 and pass outward through the port 58, leadinginto the pipe 52, and thence along the pipe 48 to the pump 41. From theremaining port connection 88 of the pump 41 the line 8| leads to themiddle port 82 of the fluid distributing valve, generally designated 83,and having a longitudinal bore 84 within which is reciprocably mounted avalve stem 55, having spaced heads 88 and 81. From. the

leads to the line-334. From the port 18 into the opposite end of thevalve 83 the line 1| leads to the control valve, generally designated12, in'a manner described below.

The fluid distributing valve contains a pair of spaced side ports 13 and14, respectively. The port 13 opens into the line 15, leading to 'theport 18 in the right-hand clamping cylinder l2. Communication betweenthe right-hand and leftport 88, in one end of the-valve 83, the line 88'hand clamping cylinders I2 is established by the pipe 11 interconnectingthe ports 18 and 18, re-

spectively, in the clamping cylinders l2. From N the other side port 14,of the fluid distributing valve 83, the line leads to the port 8| in themain pressing cylinder I]. Y

The control valve 12 is provided with a bore 82, within whichreciprocates a valve stem 83 having spaced heads 84 and 85 mountedthereon. Attached to the opposite side of the valve head 85 is the pilotplunger 88, the "latter being reciprocably mounted in the pilot bore 81of the valve. To the port 88 of the pilot bore 81 run pipelines 89 and90, and a connection with the pipeline 8| runs from the pump 41 to thefluid distributing valve 83.

with its heads 84 and 85; is urged in one direc- 10 tion by the coilspring 9|, the tension of which is adjusted by turning the threaded plug92. The lines 93 and 94,1eadingfrom the ports 95 and 98 in the valvebore 82, connect to the line 91 running back to the surge, tank 3|, andprovided means of disposing of any fluid which leaks past. the valveheads or plungers into the space behind them.

The side port 98 is supplied with pressure fluid through the line 99, inany suitable mann r, either by a'connection to the main pump 41, ong theline I 00, or else through the dotted connection ill to theauxiliarypump I02, from which the suction line I03 runs back to the surge tank3|. The remaining side port I04 of the control valve 12 is connected tothe line 1|, running to the end port 18 in the fluid. distributing valve63.

The pump 41 may be of any suitable type, preferably of a reversibletype. It will be understood, however, that areversing valve may beemployed to reverse the direction of flow of the fluid from the pump41in place of using a reversible pump, without departing from'the spiritof my invention.

In theoperation of the circuit of my invention, the metal blank I 0 isplaced upon the lower die 5 member 6. The pump 41 is started and themain prevents the main plunger I8 from moving ahead,"

of the blank holder 25.

r 0 Meanwhile, the pump 41 has been discharging pressure fluid into theline GI and the central chamber of the fluid distributing valve 63. The

fluid passes outward through the port 13, to the line 15, through theport 16 into the right-hand 50 clamping cylinder |2, whence it proceedsthrough e port 18 and along tha line 11, through the port 19 into theleft-hand clamping cylinder I2.

' This pressure causes the clamping plungers 2| to move downward,carrying with them the main 55 plunger I8 by reason of theirinterengagement at; the shouldered portions 30 on the tie member 22.

As soon as the blank holder 25 has made contact with the blank I0, theresistance encountered causes pressure to be built up in the clampingcyl- 60 inders I2 and in the lines leading through the fluiddistributing valve 53 to the connection 60 of the pump 41, this pressurebeing conveyed along the lines 90 and 89, through the port 88 into thepilot bore 81? This pressure acts against the 5 pilot plunger 86 in sucha manner as toforce the valve stem 83 and its spaced heads 84 and 85upward. Pressure fluid is ,then discharged either from the connectionI00 of the line 99 to the line 90-, leading to the main pump" 41, orelse 7 to the connection |0| leading to the auxiliary pump I02. g

This pressure fluid discharges through the port 88 in the middle chamberof the control valve 82,

and passes outward through the port I04, along the line 1| and throughthe port 10, into the lower The valve stem 83,

endchamber of the fluid distributing valve 83. This pressure forces thevalve head 8'. upward, cutting of! the connection of the clampingcylinders 2 to the valve 63 by way of the port 18,

and enabling the pressure fluid received along-the 5 line 5| from thepump 41, to be discharged through the port 14 of the valve 83, the line80 and the port 8|, into the main pressing cylinder II above thepressing plunger I8. The pressure fluid thus received forces the mainplunger downward and completes the drawing operation upon the metalblank I0 by forcing he upper die member 20 into the forming portio 1 ofthe lower die member 8, with the metal blank I0 therebetween. Meanwhile,the pressure fluid operating the clamping plungers 2| has been entrappedwithin the clamping cylinders I2.

At the same time, the fluid forced out of the space beneath the pressingplunger I8 passes outward through the port 5| inthe main cylinder I I,through the pipes 50 and 53, and the port 58 of the relief valve 54 actsagainst the relief valve plunger 55 in such a manner as to force itbackward and permit the fluid to escape through the port 59 and thelines 52 and 48, leading back to the port connection 46 of the. pump 41.During these operations the surge valves 32 automatically remain closedby reason of the pressure exerted upon them, permitting nodischarge ofthe fluid in the upper parts of the cylinders II and I 2' into the surgetank 3|.

When the drawing or pressing operations have been completed, thedirection of flow of the pressure fluid from the pump 41 is reversed, asby shifting the control lever. H0, whereupon the pump 41 now dischargesinto the lines 45 and 48.

' The fluid discharged through. the line 48 passes through thecheckvalve 49, along the line 50, through the port 5| into the space beneaththe main pressing plunger l8, forcing the latter upward and retractingthe main platen l9 and the upper die member 20. The same action causesthe clamping plungers to be retracted through the shouldered connection30 of their tie member 22 with the platen I 9.

The pressure fluid in the line flows downward through the branch line 69and the upper end port 68, into the upper end chamber of the fluiddistributing valve 63. This pressure fluid acts against the valve head68, forcing it downward and closing the connection through the port 14to the line 80. This same action opens the connection from the clampingcylinders I2,

through the port 16, the line 15 and port 13, into the middle chamber ofthe fluid distributing valve 83, thence through the port 62 and line 8|,

into the connection.60 of the pump 41, this con- 1 nectionjli in' thereversed position ofthe pump being a suction connection.

Meanwhile, the fluid in the upper portions of the cylinders II and I2 ispermitted to pass back into the surge tank 3| through the surge valves32, the latter being operated to accomplish this by the pressure fluidreaching them along the lines 45 and 33 from the pump 41. This manner ofoperation of these surge valves 32 is disclosed in my prior patent, No.1,892,568, previously referfed to.

With the pump 41 in its reversed position, lines 90 and 89, leading fromthe line 8|, are caused to become'suction lin'esfreleasing the pressureagainst the pilot plunger 85 of the control valve 12'. This allows thevalve stem 83, with its heads 84' and 85, to move downward, closing theconventing pressure fluid from flowing along the line H into the lowerend chamberof the fluid distributing valve 63. The fluid escaping fromthe latter, however, passes through the upper end chamber of the controlvalve.'l2, through the opposite port 96 and line 94 thereof, along theline 91 to the surge tank ii.

The discharge of the fluid from the auxiliary pump I02, if such beused,- may baby-passed by a suitable ,by-pass or relief valve I05,fdrming a bridge throughthe lines I06 and I01 between the opposite portsof the pump I02. Alternatively, a pump of the variable delivery type maybe used as an auxiliary pump I02, this pump having a servo-piston which,at a predetermined pressure, shifts the shift ring ofthe pump to itsneutral position, and causes the discharge from the pump to cease. Thismechanism is well known to those skilled in the art, and forms no partof the present invention.

j During the return stroke more oil is displaced from the space abovethe main plunger I8 than is forced into the annular space beneath it,because of the volume occupied by the piston rod I71.

This excess oil is returned to the surge tank 3|- through the surge'valve 32,- in' the manner pre-- viously described. A make-up checkvalve 44 is provided in the line 34 to supply the pump with oil.on thedownward or pressure stroke. During the downward stroke of the mainplunger 18 the relief valve 54 prevents coasting of the platen is anddie member 20 at the moment the clamping member 23 and blank holderengage the workpiece or blank I. v

I desire to comprehend within my invention such modiflcations as may beembraced within my claims and the scope of my invention.

Having thus fully described my invention, what- I claim as new anddesire to secure by Letters Patent, is: V

1. In combination, a pressing cylinder, a-pressing plunger therein, aclamping cylinder, a clamping plunger therein, a source of pressurefluid,-a

valve arranged in one position to direct pressure fluid into theclamping cylinder and in another position to direct pressure fluid intothe pressing cylinder, and means responsive to the attainment of apredetermined pressure in one of said 'cylinders for shifting said valvefrom one position to the other position.

2. In combination, a pressing cyllnder, a press-- in: plunger therein, aclamping cylinder, a clamping plunger therein, a source of pressurefluid, a

valve arranged in one position :to direct pressure fluid in to theclamping cylinder-and in another position to direct pressure fluid intothe pressing cylinder, and means responsive to the attainment of apredetermined pressure in said clamping cylinder to shift said valve todirect pressure fluid into said pressing cylinder.

3. In combination, a pressing cylinder, a double-acting pressing plungertherein, a clamping cylinder, a clamping plunger therein, a source ofpressure fluid, a valve arranged in one position ii) direct the pressurefluid'into the clamping cylinder and in another" position to directpressure rfluid into the pressing cylinder, automatically ing plungertherein, a clamping cylinder, a clamping plunger therein, a source ofpressure fluid,

'a single distributing valve arranged in a flrst position to direct thedischarge of fluid from said source into said clamping cylinder only andin a second position to direct pressure fluid into said 1 pressingcylinder, and means responsive to the attainment of a predeterminedpressure in said clamping cylinder to shift said valve and therepressurefluid, a valve arranged in one position to direct the pressure fluidinto' the clamping cylinder and in another position to direct pressurefluid into the pressing cylinder, means responsive to the attainment ofa predetermined pressure in 'said clamping cylinder to shift said valvefrom said first-mentioned position to said last-mentioned position,means to reverse the direction of flow fromsaid source to saidcylinders, and means responsive to saidreversal to shift said valve torelease the fluid from said clamping cylinder.

6. In combination, a pressing cylinder, a pressing plunger therein, aclamping cylinder, a clamping plunger therein, a source of pressurefluid, a valve arranged in one position to effect the dischargeofpressure fluid from said source into said clamping cylinder, and meansresponsive to the attainment of a predetermined pressure in saidclamping cylinder to shift said valve and direct said pressure fluidinto said pressing cylinder. -.7. In combination, a pressing cylinder, apressing plunger therein, a clamping cylinder, a clamping plungertherein,.a source of pressure fluid, a

valve arranged in one position to effect the discharge of pressure fluidfrom said source into said clamping cylinder, means responsive to theattainment of a predetermined pressure in said Yclamping cylinder toshift said valve and direct said pressure fluid into said pressingcylinder,and

means responsive'to the shifting of said valve to entrap the pressurefluid within said clamping cylinder and to supply pressure fluid to saidpressing cylinder.

valve arranged in one position to effect the discharge of pressure fluidfrom said source into said clamping cylinder, hydraulic means responsiveto the attainment of apredetermined pressure in said clamping cylinderfor shifting said valve into a position for directing said pressurefluid into said pressing cylinder, and a control valve arranged tocontrol the admission of pressure fluid to said hydraulic shiftingmeans.

9. In combination, a pressing cylinder, a pressing plunger thereinhaving piston areas associated therewith for advancing and retractingsaid pressing plunger, a clamping cylinder, a clamp ing plunger therein,a source of pressure fluid having associated therewith means forselectively delivering pressure fluid to said piston areas for advancingand retracting said pressing plunger, a distributing valve connected tosaid source of pressure fluid, said valve having associated therewithhydraulic means for shifting said valve from a first position fornormally directing pressure fluid into said clamping cylinder to asecond position for directing pressure fluid into said pressingcylinder, and a control valve having associated inder ,and meansresponsive to the attainment of pump, a valve arranged in one positionto discharge pressure fluid from said pump into said clamping cylinderand in another position to discharge said pressure fluid into saidpressing cyla predetermined pressure in said clamping cylinder to shiftsaid valve from said first-mentioned to said last-mentioned position.

11. In combination, a pressing cylinder, areversible pressing plungertherein, a clamping cylinder, a clamping plunger therein, a source ofpressure fluid, a reversible pump, a valve arranged in one position todischarge pressure fluid from said pump into said, clamping cylinder andin another position to entrap the previously discharged pressure fluidwithin said clamping cylinder and subsequently discharge said pressurefluid into said pressing cylinder, and means responsive to theattainment of a predetermined pressure in said clamping cylinder toshift said valve from said first-mentioned to said last'-mentionedposition.

12. In combination, a pressing cylinder, a reversible pressing plungertherein, a clamping cylinder, a clamping plunger therein, a source ofpressure fluid, a reversible pump, a. valve arranged in one position todischarge pressure fluid from said pump into said clamping cylinder andin another position to entrap the previously discharged pressure fluidwithin said clamping cylinder and subsequently discharge said pressurefluid into said pressing cylinder, means responsive to the attainment ofa predetermined pressure in said clamping cylinder to shift said valvefrom said first-mentioned to said last-mentioned position, meansresponsive to the reversal of said pump to shift said valve to releasethe fluid within said clamping cylinder, and means to direct pressurefluid to the opposite side of said pressing plunger to retract saidpressing plunger.

13. In combination, a pressing cylinder, a reversible pressing plungertherein, a clamping cylinder, a clamping plunger therein, a source ofpressure fluid, a reversible pump, a valve arranged in one position todischarge pressure fluid from said pump into said clamping cylinder andin another pomtion to entrap the previously discharged pressure fluidwithin said clamping cylinder and subsequently discharge said pressurefluid into said pressing cylinder, means responsive to the attainment ofa predetermined pressure in said clamping cylinder to shift said valvefrom said first-mentioned to said last-mentioned position, meansrespoiisive to the reversal of said pump to shift said valve to releasethe fluid within said clamping cylinder, and means to'direct pres'surefluid to the opposite side of said pressing plunger to retract saidpressing plunger, said 10 clamping plunger and said pressing plungerhaving interconnecting means adapted to cause the retraction of saidclamping plunger upon the retraction of said pressing plunger by thereversal of said pump. 15

14. In combination, a pressing cylinder, a reversible pressing plungertherein, a clamping cylinder, a' clamping plunger therein, a reversiblepump. a valve arranged in one position to discharge pressure fluid fromsaid pump into said clamping cylinder and in another position todischarge said pressui'e fluid into said pressing cylinder, hydraulicmeans for shifting said valve from one position to the other, and acontrol valve responsive to the attainment ofa predetermined pressure insaid clamping cylinder to admit pressure fluid to shift said valve.

15. In combination, a pressing cylinder, a reversible pressing plungertherein, a clamping cylinder, a clamping plunger therein, a reversiblepump, a valve arranged in one position to discharge pressure fluid fromsaid pump into said clamping cylinder and in another position todischarge said pressure fluid into said pressing cyl-- inder, hydraulicmeans for shifting said valve from one position to the other, a controlvalve responsive to the attainment of a predetermined pressure in saidclamping cylinder to admit pressure fluid to shift said valve, and anauxiliary pump for supplying pressure fluid to said control 4 of thepressing plunger, and means responsive to the attainment of apredetermined pressure in said clamping cylinder to shift said valvefrom said one position to said other position.

WAL'IER ERNST.

